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SYSTEMATIC NAME

IUBMB Comments

tRNA-guanosine34:queuine tRNA-D-ribosyltransferase

Certain prokaryotic and eukaryotic tRNAs contain the modified base queuine at position 34. In eukaryotes queuine is salvaged from food and incorporated into tRNA directly via a base-exchange reaction, replacing guanine. In eubacteria, which produce queuine de novo, the enzyme catalyses the exchange of guanine with the queuine precursor preQ1, which is ultimately modified to queuosine [4,5]. The eubacterial enzyme can also use an earlier intermediate, preQ0, to replace guanine in unmodified tRNATyr and tRNAAsn [2]. This enzyme acts after EC 1.7.1.13, preQ1 synthase, in the queuine-biosynthesis pathway.

the TGT-RNA covalent complex is kinetically capable of occurring on the TGT reaction pathway. Dissociation of product RNA from the enzyme is overall rate-limiting in the steady state. Role for the 2'-hydroxyl group of the ribose in the TGT reaction

the enzyme is responsible for the posttranscriptional modification of specific tRNAs (Asn, Asp, His and Tyr) with queuine. The enzyme catalyzes base exchange of guanosine34 with 7-aminomethyl-7-deazaguanine

the tRNA-modifying enzyme catalyzes the posttranscriptional exchange of guanine in position 34 of tRNA(Y, H, N, D) with the modified base queuine in eukaryotes or its precursor, preQ(1) base in eubacteria

higher expression of the subunit TGT60KD in cancer cells than in normal cells. The expression levels of the TGT60KD subunit regulate enzyme activity and the level of queuosine. TGT60KD plays significant roles in carcinogenesis

the enzyme is responsible for the posttranscriptional modification of specific tRNAs (Asn, Asp, His and Tyr) with queuine. The enzyme catalyzes base exchange of guanosine34 with 7-aminomethyl-7-deazaguanine

the tRNA-modifying enzyme catalyzes the posttranscriptional exchange of guanine in position 34 of tRNA(Y, H, N, D) with the modified base queuine in eukaryotes or its precursor, preQ(1) base in eubacteria

higher expression of the subunit TGT60KD in cancer cells than in normal cells. The expression levels of the TGT60KD subunit regulate enzyme activity and the level of queuosine. TGT60KD plays significant roles in carcinogenesis

addresses a hydrophobic subpocket close to the dimer interface that may affect quarternary structure formation, prevents the formation of the catalytically active Tgt:tRNA complex, and can disrupt the preformed complex

addresses a hydrophobic subpocket close to the dimer interface that may affect quarternary structure formation, prevents the formation of the catalytically active Tgt:tRNA complex, and can disrupt the preformed complex

2 * 19000 + 2 * 54000, archaeosine tRNAguanine transglycosylase is classified into full-size or split types. Although the full-size type forms a homodimeric structure, the split type forms a heterotetrameric structure, consisting of two kinds of peptide. Interaction between the two subunits may contribute to the conformational stability of split ArcTGT

2 * 19000 + 2 * 54000, archaeosine tRNAguanine transglycosylase is classified into full-size or split types. Although the full-size type forms a homodimeric structure, the split type forms a heterotetrameric structure, consisting of two kinds of peptide. Interaction between the two subunits may contribute to the conformational stability of split ArcTGT

2 * 19000 + 2 * 54000, archaeosine tRNAguanine transglycosylase is classified into full-size or split types. Although the full-size type forms a homodimeric structure, the split type forms a heterotetrameric structure, consisting of two kinds of peptide. Interaction between the two subunits may contribute to the conformational stability of split ArcTGT

2 * 19000 + 2 * 54000, archaeosine tRNAguanine transglycosylase is classified into full-size or split types. Although the full-size type forms a homodimeric structure, the split type forms a heterotetrameric structure, consisting of two kinds of peptide. Interaction between the two subunits may contribute to the conformational stability of split ArcTGT

2-aminolin-benzoguanine inhibitors in complex with TGT, by hanging-drop, vapor diffusion method at 0°C and macro-seeding, to 1.28-1.78 A resolution, crystals belong to space group C2. The 2-amino-lin-benzoguanines are protonated upon binding to TGT. At pH 5.5, Asp102 is rotated to 75% into the guanine binding pocket whereas at pH 8.5 the same residue is oriented to 100% out of the pocket. Pronounced disorder of the attached side chains addressing the ribose 33 binding pocket

mutant K52M, by hanging-drop, vapor-diffusion method and followed by macroseeding, at a resolution of 2.0 A, forms crystals under the same conditions as wild-type, while all attempts to obtain diffracting crystals from mutant Y330F are unsuccessful. Compared to wild-type, crystals of mutant K52M are very fragile and show only a limited diffraction quality

TGT in complex with 6-amino-4-{2-[(cyclohexylmethyl)amino]ethyl}-2-(methylamino)-1,7-dihydro-8H-imidazo[4,5-g]quinazolin-8-one, residues Val45 and Leu68 form a hydrophobic surface that hosts the cyclohexane ring

wild-type at pH 5.5 to 1.9 A resolution and in complex with pre-queuine 0 to 1.7 A resolution (both crystals belong to space group C2), and in complex with its natural substrate pre-queuine 1 to 2.4 A resolution (crystal belongs to space group C2221). Mutant Y106F alone to 1.95 A resolution and in complex with pre-queuine 1 to 1.9 A resolution (both crystals belong to space group C2). By macroseeding and the hanging-drop method

reduced turnover value. At a concentration of protein of 0.01 mM appears almost exclusively as a homodimer as the wild-type, when the concentration of protein is lowered to a minimal value of 0.001 mM, a substantial proportion of monomer becomes evident

reduced turnover value. At a concentration of protein of 0.01 mM reveals a significant amount of monomer, when the concentration of protein is lowered to a minimal value of 0.001 mM, a substantial proportion of monomer becomes evident

2.8fold decrease in turnover-number for guanine and tRNA, 2.8fold decrease in Km-value for tRNA, 3.4fold increase in turnover-number for guanine, in contrast to Phe106 the residue Tyr106 is hydrogen bonded in the ligand-free structure, this is not the reason for the kinetic difference, other structurally less evident factors are responsible for this behaviour